How about using Mail::Internet instead? Here's how I'm using it, which works well:

use strict; 
use warnings;

use Mail::Internet;     # parse incoming headers
                        # from a stream, could be
                        # a file handle too.. 

my $message     = new Mail::Internet ([<>]);   
my $from        = $message->get('From');
my $subject     = $message->get('Subject');
my @body        = @{$message->body()};

# ..print or manipulate as normal.
[download]

In my code, I'm using Mail::Internet , MIME::Lite (thanks ar0n for the tip), and Config::Simple to parse a template out of an email message sent to my script, operate on the variables parsed from that template, and send the sender back a binary file which includes the data requested in the template, as a file attachment to the reply.

These modules let me grab all the headers, body, and manipulate them/parse them for my needs. It works very well, and is incredibly small and fast.